A private line data network shared in parallel by a plurality of terminal stations whose operations are controlled from a remote control station is known as a multipoint or party line. The control station is equipped with a master controller, such as a computer, which can communicate with any of the terminal stations, instructing the terminal stations to transmit messages to the computer station which stores and possibly processes the messages thus received from the sending terminals and then possibly retransmits the messages to other terminals on the multipoint network or on other multipoint networks that may be connected to the computer.
The computer station is connected to a common carrier central office called a hub office containing a unit called a multipoint junction unit. This unit accepts the downstream signals from the control station on a main line thereof and splits the signals for application to branch lines to further convey or broadcast the signals in the downstream direction towards terminal stations, to other local offices or to other hub offices further downstream. In the latter case, the signals applied to the main line of the downstream junction unit are split again to be broadcast to branch lines radiating from the downstream hub to the terminals connected thereto. In the upstream direction, transmission from a downstream terminal passes to the branch line in the downstream hub office where the signal is combined by the multipoint junction unit with signals on other branch lines and the resultant signals are applied to the main line of the downstream unit. These signals are propagated up to a branch in the upstream hub office, combined with signals on other branches and transmitted upstream to the computer station subject to the condition that only one station at a time can send to the computer station.
It is a known function of the common carrier to provide appropriate administrative or housekeeping chores for the network, which function includes selecting one or more branch lines, to the exclusion of others, to constitute the data network or, alternatively, removing or blocking one of more branch lines to take those blocked branches out of the network. In U.S. Pat. No. 4,122,301, which issued to L. M. Kolensky, W. R. Schaefer, G. G. Schlanger and A. H. Willand, there is disclosed a multipoint network provided with multipoint junction units that permit exclusive data intercommunication with or block data intercommunication with selected branches when certain selection (or blocking) codes are applied to main lines thereof. Accordingly, to appropriately configure the network, an attendant at the upstream hub office first ascertains which branches are to be selected to either provide exclusive data interchange or to be blocked. The attendant then operates hub office control equipment to send appropriate selection codes to the main line of the upstream junction unit if an upstream branch is to be selected. When a downstream branch is to be selected, the attendant first sends the selection code which selects the upstream branch (connected to the downstream unit) for exclusive data interchange and then sends the selection code which selects the appropriate downstream branch (for exclusive data interchange or blockage). Each junction unit is arranged to report back its selection operations so that the attendant can observe the configuring of the network.
It is sometimes desirable, for private line data networks, to be able to configure the network from the remote control location. This location, however, may be under control of a carrier subscriber rather than the common carrier and this subscriber may not know which downstream branches are connected to the network terminals, which upstream branches are connected to the downstream units and which selection codes will select these various branches. It is therefore a broad object of this invention to configure the network from a remote location without knowledge of the selection codes or the network "mapping."